"Dave J" wrote in message
...
On Mon, 10 Oct 2005 11:33:07 -0400, John Grabowski
wrote:
What do you think will happen? I think it will burn up the insulation on
the wire.

Not likely. Resistance of 6 gauge wire is 0.47 ohms per 1,000
feet. I have 160 feet (going both ways), which makes resistance equal
to 160*0.47/1000 = 0.075 ohm. At 100 amps, a 0.047 ohm resistor
would produce 7.5 watts of power total, a negligible amount.

http://www.bnoack.com/index.html?htt...esistance.html

Is my calculation wrong?

Dave J


Yep! Wrong. Two things. My wire tables show 0.39 Ohms per thousand. Also,
the formula for power consumed in a resistor is I *squared* times the
resistance. Hence, 100 x 100 x 0.39 x 160/1000 = 624 Watts *total*, or
624/80 = 7.8 Watts *per foot* of conduit.


"Dave J" wrote in message
...
I have a subpanel that is about 80 feet away from the main panel. It
uses 6 gauge copper THHN wires conducting 220V current, in a 3/4"
raceway. What will happen if I upgrade the breakers to 100 A and try
to use close to 100A of 220V. Thanks, Dave J.




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